Field
The invention is in the field of fire-retardant compositions and of processes for producing them.
State of the Art
Boric acid in powder form has long been used as a fire retardant for cellulosic materials, such as cotton batting and ground waste paper insulation. Boric acid is traditionally produced by treating a borax solution with sulfuric acid and recovering the boric acid crystals that form upon cooling the solution. Boric acid has been made directly from a borate ore by the procedural steps of pulverizing the ore, mixing the resulting powder with water to form an aqueous slurry, mixing the slurry with sulfuric acid, separating the resulting solids from the solution, crystallizing boric acid by cooling the solution, and separating the boric acid crystals from the residual solution. Whether made from borax or from a borate ore, the product has been a commercially pure boric acid. The elimination of sulfates has been regarded as necessary when utilizing ore as the source material.